Improvement in thermometers



y waxing land silvering, it. six.-sevenths (-l) of the whole time occupied UNITED STATES PATENT OFFICE.

MICHAEL A. FINNELL, ou .New YORK, ur.

.'iMPaovE-MENT |N;THERMoMETERs..

Specification forming partof .Letters Patent No. 33,935,1ated December- 17, 1851.'

Ib au whom imayconcern:

Be it known that I, MroHAnnA. FINNELL, ot" 132 West Houston street, in the-city,

county, and State of New York, have invented.

certain new' `and useful 'Improvements' in Thermometers; and 1 do hereby declare that the followingis a full, clear, and exact descriptonoi the sama-.reference being had tothe accompanying drawings, forming'partof this specication, in which` 'f Figure l isa lface View of a thermometer- .constructed according to my invention; Fig. 2, a central vertical section of the same; and Figs. A, 13(5, D, E, andlf represent a gradational series of scales'.

The object of Ithese improvements is vto manufacture .thermometers at a very greatly reducedcost. The first improvement relates tothe scales. To explain its natural will first state that, owing to the practical impossibilityof making the glass, tubes .and their bulbs exactly of'a definite orgiven size', there will bea' considerable" variation in the rangef expansion of the mercury in a number of tubesinteuded io be as nearly as possible of the. sainesize. The scales have been hereto-- fore mostl commonly constructed `by engraving 'the degrees, gures, letters, zinc., by hand upon metal plates, and each' scale hasbeen vdivided to suit thc particular tube to which it is applied byl first ascertaining -therange -of expansion of the vmercury or spirit in the tube between two givenT points 'of temperature and1marking'upon the tube the limits 0f such range, next placing the tube on the scale and marking thereon the two degrees to correspo'nd Witlithe. marks on- 'the tube, 'then dividing the scale'between those points into the requisite number oi parts to represent the intermediated'egreesand dividingthe remainder of the scale to correspond and aiterward enf gravi'ng it, stamping the letters and figures, This process takes in the manufacture .of the thermometer, and when 'completed the degrees are seldom accu# rate. Instead lof using this process ofcoustruction, I provide a series Ogradational scales printed upon paper or other suitable material, and after having ascertained and marked upon a tube the rang* of the expansion ojthe mercury or'spirit within it between' twosuitable poi-nts oi' temperature I select; frommy scales one whose' graduation corresponds in those points with 'the marks on the tube and attach the tube to the scale. As the scale is equally divided into degrees, its graduation, being correct at the two points first marked on the tube,'will be correct throughout.

Thedrawings represent a series of six printed scales, which is a sufficient'number to illustrate my inventiomthough I propose to use a much larger numbersay tWenty-iive-the second scale B being -longer` than A byoneforteth (11W) partvoflA; 'the third"C,longer than B. by one -fortieth (1,16) part of B; the fourthD, longer than C by one-fortieth (g5) Vpart of C, and so on throughout the series, di-

vidingthe .several scales into the same number of equal parts and numbering the degrees in the same manner in every one-as, for inl l stance, dividing each into one hundred equal` parts, representing two hundred degrees, and' numberingjt fromeOfbelow to 160 above ze'ro. The aboveament-ione'd number of divrisionsnvith' a progressive increase of onefortietli A(2116) in the lengthof the scales, gives 'an increase from scale to scale equal to 5,

and hence., as @gir/l0, there will bean increase'of' only 1'in everyf40., and 'consequently byxtting a glass tothe scale which nearest. .approximates to' the two marks'indicatingthe rangejofexpansion of the mercury or spirit lwithin it a correct injd'cation of' tcmperatureis obtained. The division of the engraved plates or blocks from which the scales are printed may be obtained by means ofa divding-engine, and by that vmeans in uch greater correctness of indication th roughout the whole range of expansion may be obtainedthan is done with the metal scalesl divided and cutby hand, which. are'necessarily liable to inaccuracies.

. Iii-order to 'reduce the cost as much as' pos-` sible, I propose to print vthe scale on a stout candor piece of card-board or pasteboard or bristol-board,which may also constitute the case or back of'the thermometexyas shown in Figs'.-1 and 2, inwhich G is the lc artfl and H thetube. This card may'beornamented taste A ifully at little expense by lithographie or other printing, by which. process 'the scale may be produced at the same time. In order to enable the tube to lie closeagainst the plane Prepared Glue.

surface of the so-constructed scale or against any fiat scale or plane surface and be attached closely thereto without cutting or providing a hole in the said scale or surface for the 'reception of the bulb, my second improvement consists in bending thetube close to or near the bulb to throw the bulb forward to a sulicient distance, as illustrated in the section, Fig. 2, in which the bend ais represented just above the bulb b, which, with nearly the whole length of. the tube, is shown to lie close against the card. i A

My third improvement consists in aflxing the tube to its scale bymeans of a suitable adhesive substance, thereby dispensing with the loops, wiring,- or other means of attachment heretofore adopted and producing,r a much neater appearance. lVarious materials might be used for this purpose; but that which AI prefer is what is known and sold in most places in the United States as Spaldings Thermometers' having their scales printed upon paper may bemadeso light and convenient that they may be inserted without vdifficulty in walking-canes, hats, umbrellas,

watches, clocks, breast-pins, looking-glasses,

. a Y:manu

picture-frames, dagu erreotype-cases, business vshow-cards, sewing-machines, ladies Workboard as the material for printed thermometerscales, as and for the purposes set forth.

2. Securing the tube to such scale by celnentation, as set forth.

3. In combination with tubes thus secured; the bend near the bulb, as set forth.

4. In combination with said printed thermometer-scales, the above-described method of adapting the thermometer-tubes to their appropriate ranges of indication.

M. A. FINNELL. Witnesses:

RICHARDSON GAWLEY, JAMES LAIRD. 

